15 The Sand Beach Ecosystem of Chile
E. JARAMILLO
15.1 Introduction
The Chilean coast extends for about 4,200 km. South of Chiloe Island the
coast (42-56°S) is characterized by archipelagos, fjords, channels, and
islands, owing to the sinking of the Chilean longitudinal Central Valley.
Exposed sandy beaches of different morphodynamic types alternate with
intertidal sand flats at the mouth of rivers in south-central Chile between
38°S and 42°S and with rocky peninsulas in the extreme north (19-30°S;
Fig. 15.1). Seasonal cycles of beach sand erosion and accretion are typical.
During erosion, beaches have concave profiles with coarser grained sand
than during accretion periods, when profiles are convex.
15.2 Environmental Setting
The influence of different ocean currents causes a gradual northward
increase of seawater temperatures (Viviani 1979; Brattstrom and Johanssen 1983). Spring-tide winter and summer water temperatures in the surf
zone at Mar Brava (42°S) and Aguila (21°S) range from 12 to 14.5°C and
from 17 to 18.8 oc, respectively (Fig. 15.1). The northern coast (19-30°S) is
characteristic of a dry desert climate with low and irregular precipitation
(Di Castri and Hajek 1976) and mean monthly air temperatures between
18 and 22 oc in the summer and 12 to 17 °C in the winter. Further south,
along a warm-temperate zone (30-38°S), annual precipitation and mean
monthly temperature are 110 mm and 15-22 oc at 30°S and 760 mm and
10-13 oc at 38°S (Brattstrom and Johanssen 1983), respectively. In the rainy
Patagonia-Tierra del Fuego zone (38-56°S) mean annual temperatures
decrease from 12.5 °C (38°S) to 5.4 °C at Cape Horn (56°S).
Ecological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
©Springer-Verlag Berlin Heidelberg 2001
E. JARAMILLO
15.1 Introduction
The Chilean coast extends for about 4,200 km. South of Chiloe Island the
coast (42-56°S) is characterized by archipelagos, fjords, channels, and
islands, owing to the sinking of the Chilean longitudinal Central Valley.
Exposed sandy beaches of different morphodynamic types alternate with
intertidal sand flats at the mouth of rivers in south-central Chile between
38°S and 42°S and with rocky peninsulas in the extreme north (19-30°S;
Fig. 15.1). Seasonal cycles of beach sand erosion and accretion are typical.
During erosion, beaches have concave profiles with coarser grained sand
than during accretion periods, when profiles are convex.
15.2 Environmental Setting
The influence of different ocean currents causes a gradual northward
increase of seawater temperatures (Viviani 1979; Brattstrom and Johanssen 1983). Spring-tide winter and summer water temperatures in the surf
zone at Mar Brava (42°S) and Aguila (21°S) range from 12 to 14.5°C and
from 17 to 18.8 oc, respectively (Fig. 15.1). The northern coast (19-30°S) is
characteristic of a dry desert climate with low and irregular precipitation
(Di Castri and Hajek 1976) and mean monthly air temperatures between
18 and 22 oc in the summer and 12 to 17 °C in the winter. Further south,
along a warm-temperate zone (30-38°S), annual precipitation and mean
monthly temperature are 110 mm and 15-22 oc at 30°S and 760 mm and
10-13 oc at 38°S (Brattstrom and Johanssen 1983), respectively. In the rainy
Patagonia-Tierra del Fuego zone (38-56°S) mean annual temperatures
decrease from 12.5 °C (38°S) to 5.4 °C at Cape Horn (56°S).
Ecological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
©Springer-Verlag Berlin Heidelberg 2001